Part of the IRIS HAVEN garden in bloom time Sydney, Australia
LOUISIANA IRISES are an evergreen perennial with fresh green foliage and handsome, sword-like leaves, which make them an excellent landscaping accent plant both in the garden, in a bog or in a water feature.
These irises generally bloom in mid to late spring. One rhizome will give you one flowering stalk (or spike) per year. The flowering stalks usually stand above the foliage. Blooms open in random order (usually from the top of the stalk downwards or from the bottom of the stalk upwards) over an extended period. Each stalk should have a minimum of four bud placements on the stalk, with each bud placement containing a minimum of two flower buds. Buds will open for between two and four days each.
In this way a flowering stalk can remain open for in excess of 10-12 days. If you chose early, mid or late-blooming varieties (and this information is contained on this website next to each cultivar name) you can extend the bloom season considerably. The stalks are good to cut and bring inside your home so that you can enjoy them - and they are happy in a vase by themselves, or with other flowers and foliage.
Louisiana irises are very easy to grow and are relatively disease-free here in Australia. Ideally, they love a moist soil condition (it does not have to be constantly wet - just nicely moist all the time!) and acidic, with a nice amount of acidic compost added to the soil. Mulch Louisiana irises well and plant the rhizomes at least 5 cm below the soil level.
Their adaptability allows them to grow in full sun to semi-shade, with little difference in bloom quality and quantity evident, although flowering stalks can be a little taller if the plants are in a shadier location.
Their adaptability also permits them to grow in a normal garden condition, provided the soil is kept moist with a good, once-a-week watering. They will also grow well in a bog, near water, in standing pots in water or naturalised around a dam, pond or water feature. Most modern hybrids have a non-invasive nature.
The height of the flowering stalks can vary from 67 cm (28") for some of the Water Sprite varieties up to nearly 1.5 metres (4.5 feet) for the regular-height varieties. Care needs to be taken to check the height of cultivars prior to ordering so as to ensure that you have chosen appropriate cultivars for their final garden locale. Plants grown in shadier locations can also tend to grow a little taller than those grown in full sun. The heights noted on this website are for cultivars grown full sun.
Bloom sequence can vary from early to late spring. This can depend upon several aspects, including the general flowering time of the cultivar relative to your own garden location. In other words, cultvars grown in Sydney will probably bloom earlier than cultivars grown in Tasmania - but the bloom sequence will become relatively consistent with your garden locale in time. Generally speaking, bloom can occur anywhere between mid September (for Queensland) and mid November (for cooler locales).
The actual sequence of bloom season can also depend upon the particular cutlivars which you have chosen, the geographical location of your garden (as mentioned above) plus when you purchased your rhizomes. Some cultivars can take up to 12 months to settle in to their new garden location. This may mean that they might actually skip a bloom season while the rhizome concentrates on getting established. Your patience will be rewarded with increased bloom quantity later on.
Some IRIS HAVEN cultivars growing in Highland Park, Rochester, NY. USA
LOUISIANA IRISES can be grown successfully in most coastal regions of Australia. Unlike bearded irises, which can struggle in humid coastal locales and clay soils, Louisiana irises will thrive there. Basically, the further north one travels in Australia - the better your results can be.
We have customers who grow our cultivars in the sub-tropcs and tropical area of north Queensland - and even in the two-seasonal regime of Darwin and northern NT with success. We also have customers who grow our cultivars in the cooler areas of Australia like Tasmania and areas of the lower Australian Alps, southern NSW and northern Victoria.
Our Australian-bred cultivars are currently growing in Rochester, NY, USA. Rochester gets an average of 20+ inches of snow a year as well as many sub-zero days. If our cultivars will survive in Rochester, then there is not a single place in Australia where it is too cool for them!
To counter the effects of extremes in temperature (be it heat or cold) the rhizomes need to be planted under the ground and COVERED with at least 10 cm of mulch. Naturally, the mulch acts as a blanket to protect the rhizomes from whatever the extreme of weather is in their garden location. We use commercially-available sugar cane mulch for this purpose with great results - and we would happily recommend it to all for their consideration.
The rhizomes will increase quickly if they are kept moist, well mulched and well fed. We like to say that Louisiana irises are the 'teenage boys' of the iris world. In other words, the more that you feed them - the the more that they will grow!
Monthly feeding will not upset them in the slightest - and yes, we do mean monthly.
Easiest results can be achieved with the application of commercially-available camellia/azalea fertiliser, plus any other fertiliser which you have that is suitable for use on camellias and azaleas. Regular applications of Blood and Bone products is also beneficial. You can also use liquid fertilisers PROVIDED that they are suitable for camellias and azaleas.
Some IRIS HAVEN cultivars growing at Iris City Gardens, Nashville, TN, USA
As with many things in the garden, there are some DON'TS as well. So, here are the DON'TS for Louisiana irises:
DON'T use LIME OR ANY LIME-DERIVED fertiliser.
By that we mean NO Dynamic Lifter. NO Mushroom compost. NO rose fertiliser. NO potash and NO LIME!
If you have commercially-available 'all-round' products, please check the labels before applying them to your Louisiana irises. If the product states that it is suitable for camellias and azaleas (and it needs to specifically state this - not just say 'suitable for all plants'!) then it should be safe to use. Follow any instructions provided carefully as to strength and recommended applications, as over-fertilising with some of the 'all-round' products can be fatal to your acid-loving/lime-intolerant Louisiana irises.
Established clumps of Louisiana irises can remain in the garden for about 3-4 years before they benefit greatly from being lifted, divided and re-planted in freshy fertilised soil. When lifting a clump just keep the new rhizomes around the edge of the clump as these will be ones that will flower in spring. Remember - NO LIME!
We know that the 'worst drought in 100 years' conditions in Australia has remained a great challenge for gardeners for some years now. Mulching and keeping the soil just moist should be sufficient to keep your Louisiana irises happy and able to cope well. Here are a few suggestions that may assist you:
1) Put potted Louisiana irises in shallow trays - and keep the trays watered. This is a great way to save time on watering - and water itself! We use kitty-litter trays for this purpose. Just water the pots in the normal way. The tray will contain any excess water for the potted iris to take-up later on.
2) Another hint is to carefully lift your established clump of Louisiana irises in your garden. Try to keep the clump intact. In the hole where you have dug-out the clump, lay a few used plastic shopping bags flat on the ground. Then put the clump back in the garden. This way the plastic bags will act as a barrier to prevent the water from escaping from under the clump too quickly. This works a treat in sandy soil - and also adds value to the humble plastic shopping bags by recycling them sensibly.
We grow and trial our cultivars and seedlings under extremely harsh garden situations. Our soil is 80% eastern Australian seaboard clay. Our garden faces due west and is exposed to all manner of climactic challenges, including full, blazing summer sun and harsh winterwinds. We use an automatic drip watering system which is set to keep the soil JUST moist at all times - and mulching does the rest.
Customers in the hostile gardening regimes of the Australian red centre have had considerable success with our cultivars - and we have a large customer base in the US states of Arizona and southern California, where annual rainfalls of about 10-15 inches are a luxury.
It is our opinion that by growing our irises in a harsh garden regime most of our customers should encounter few problems with settling the newly-arrived rhizomes into their garden. It is our hope that our harsh garden situation will allow cultivars to over-perform in less hostile and more conducive areas.
We breed them tough so that they can perform well in almost every possible garden situation. If you keep them reasonably moist, well mulched and happily fed then you should get good results.
A two page Cultural Notes document is provided to all Iris Haven mail order customers. An Overseas Orders Information Sheet is provided to all Iris Haven overseas mail order customers. PLEASE READ THE INFORMATION PROVIDED and follow the suggestions given, as they are based on the growing experiences of fellow gardeners and customers in many different micro-climates here in Australia and overseas.
If you would like further specific cultural information, please do not hesitate to contact us as we would much rather assist you to prevent a problem then have to try to help you 'pick up the pieces' after a disaster occurs.
Happy Gardening one and all.
This page was updated on 29 JANUARY 2013